Genetic basis for face and place recoginition
The University of Michigan study titled “Nature vs. Nurture in Ventral Visual Cortex: An fMRI Study of Twins has published evidence that our brains are hardwired before birth to recognize faces and places. But in contrast, the neural circuitry we use to recognize words develops mainly as a result of experience.
Professor Thad Polk, lead author of the study comments:
“There’s been a big debate about whether face recognition is a function we’re wired to perform for survival. This is the first study to look at that question using brain imaging in twins.”
Polk and his colleagues used functional MRI to examine brain activity in sets of identical and fraternal twins who viewed pictures of faces, houses, chairs, made-up words and abstract control images. Faces, houses, and words are known to elicit distinct patterns of activity in the brain’s ventral visual cortex, on the bottom of the brain, behind and around the ears. The scientists used photos of houses to stimulate what’s called the ‘parahippocampal place area.’ They included pronounceable made-up words rather than actual words to make sure that the meaning didn’t affect brain activity. For each category the participants viewed, they had to press a button to say whether a picture was the same picture as the one before it.
The results were similar for identical and fraternal (non-identical) twins when it came to made up words, however it was a different story for places and faces. The MRIs showed that the neural pathways were the same for identical twins and not fraternal twins. This suggests that genes play a significant role in this type of brain function. Identical twins are genetic copies of one another. Fraternal twins are as genetically different as regular siblings.
“Face and place recognition are older than reading on an evolutionary scale,” Polk said. “They are shared with other species and they provide a clearer adaptive advantage. It’s therefore plausible that evolution would shape the cortical response to faces and places, but not symbols such as words and letters.”
He said that this research could help scientists understand what’s innate and what is learned. “If we can figure out the extent to which the brain can change as a result of experience and what makes it change, we could potentially develop therapies for people with brain damage,” Polk said. When parts of the brain are damaged, other areas often compensate.
Elaine Warburton
